Fuel pump venting



March 7, 1967 G. D. WOLFF 3,307,491

FUEL PUMP VENTING Filed July 15, 1965 2 Shee ts-Sheet' 1 March 7, 1957 wo I 3,367,491

FUEL PUMP VENTING Filed July 15, 1965 2 Sheets-Sheet 2 United States Patent 3,307,491 FUEL PUMP VENTING George D. Wollf, Hazel Crest, Ill., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed July 15, 1965, Ser. No. 472,194 12 Claims. (Cl. 103-203) This invention relates to venting fuel injection pumps and particularly to means for removing entrapped air from the supply chamber of a fuel injection pump.

In operating fuel injection equipment, air may become entrapped in the supply chamber of the fuel injection pump. For instance, if the fuel tank becomes empty, air will be drawn into the fuel pump. Also, during the change of nozzles it is possible for air to enter the fuel pump. Heretofore, fuel pumps have been provided with a vent screw which is removable with hand tools to effect venting of the pump. This is not convenient because the operator must leave his operators station to effect venting. Also heretofore it has been suggested that the supply chamber of a fuel pump be provided with a continuously open air vent. This type vent is effective in passing fluid as well as air, from the supply chamber to the fuel reservoir. The continuously open vent arrangement has the disadvantage of reducing the supply chamber pressure at low pump speeds. Proper fuel pump control is more difficult at low engine speed and reduction of supply pump pressure increases the difficulty of precise fuel delivery control. It has also been suggested that a special valve be provided for venting the supply chamber of a fuel injection pump to an engine intake manifold, whereby the valve is in a venting position at low supply chamber pressure but moves to a nonventin-g postion when the supply chamber pressure rises to a predetermined extent. In addition to other disadvantages, such a system has the obvious disadvantage of not venting during normal operation of the pump.

It is an object of this invention to provide an improved means for venting the supply chamber of a fuel injection p a.

It is a further object of this invention to provide a venting means for the supply chamber of a fuel injection pump which is operated manually by the operator at his regular station.

It is a further object of this invention to provide venting means for the supply chamber of a fuel injection pump which utilizes a shiftable pump control member as a valve to permit venting during a predetermined position of the control member.

It is a further object of this invention to provide means for automatically venting the supply chamber of a fuel injection pump when the manual control for the pump is in a shutoff or other nonoperating position.

These and other objects and advantages of this invention will be apparent to those familiar with the art when the following description is read in conjunction with the drawings, in which:

FIG. 1 is a top view of a pump incorporating this invention with parts broken away to shown details of consrtuction;

FIG. 2 is a side view of the pump shown in FIG. 1 also having parts broken away to show details;

FIG. 3 is a section view taken along the line IIIIII in FIG. 1;

FIG. 4 is a view showing the pump control member in a venting position; and

FIG. 5 is a schematic view showing control linkage between the operator station and the pump control member.

- Referring to FIGS. 1 and 2 of the drawings, I illustrate my invention in a distributor type fuel injection pump assembly which includes an injection pump 11 and governor 12. The pump and governor are installed in a housing 13 made up of a pump section 14 in which pump 11 is incorporated and a governor section 16 in which the governor 12 is incorporated. A wall 17 of pump section 14 divides the governor compartment or chamber 18 from a fuel supply chamber 19.

An engine driven pump drive shaft 21 reciprocates a pump plunger 22, in a bore 23 in the head portion 24 of the pump section of housing 13, by a cam 26 acting through tappet roller 27 and tappet cup 28-. The pump plunger 22 is rotated by the drive shaft 21 through gear 31 on drive shaft 21, gear 32 connected for rotation with plunger 22 and gear cluster 33 which includes gears 34, 35. Gears 31 and 35 constitute a supply pump which draws fuel from a reservoir 36 and delivers it to the supply chamber 19 by passage means, not shown. The fuel supply chamber 19 is maintained at an intermediate pressure, such as 50 pounds per square inch, by a regulating valve 37 in wall 17. Excess fuel in the supply chamber 19 is spilled by regulating valve 37 to the governor compartment 18 from which it is returned to the reservoir 36 by way of exhaust port 39.

As the pump plunger 22 is reciprocated and rotated by the drive mechanism, fuel is permitted to enter the pumping chamber 41 at the upper end of bore 23 by way of inlet passages 42, 43 under the control of a control sleeve 44. Plunger 22 of the illustrated pump has six pumping strokes during one revolution of the plunger and during the six pumping strokes a delivery port 46 in the plunger registers successively with the six delivery passages 47. The delivery passages 47 are adapted for connection to injectors at the six cylinders of an engine on which the illustrated pump assembly may be installed.

The control sleeve 44 is shiftable axially and rotataby relative to the housing 13 by axial and rotative shifting, respectively, of a control members or rod 51. The control rod 51 mounted in aligned bores 65, 67 in housing 13 for rotative and axial movement and has a pressure equalizing axial passage 70 placing cavity in fluid communication with governor chamber 18. When the control rod is in its fuel delivery (idle) position illustrated in FIGS. 1, 2 and 3, fuel is delivered to the delivery passages 47. However, when the control rod 51 is shifted axially to its fuel shutoff position illustrated in FIGS. 4 and 5, no fuel is delivered by the pump through the delivery passage 47 because recesses 52 of the control sleeve 44 register with inlet ports 43 during the upward or pumping stroke of the plunger 22. The distributor portion 56 of the plunger 22, which includes the delivery port 46, includes a recess 57 extending somewhat more than halfway circumferentially about the plunger and an axial groove 58 which connects recess 57 with the supply chamber 19. The recess 57 and groove 58 are not connected to delivery port 46 but instead serve to connect the delivery passages 47 to the supply chamber during the major portion of the time that they are not in registry with the delivery port 46.

Under certain conditions air will become entrapped in the supply chamber 19 resulting in abnormal pump operation. Air may enter the supply chamber as a result of changing injectors and also as a result of running out of fuel during operation. Although, heretofore it has been suggested that a vent be employed in an exterior supply chamber wall with a removable plug, such construction has necessitated the operator leaving the operators station and thus stopping operation of the equipment while he unscrewed the vent screw to exhaust entrapped air from the supply chamber.

I provide a venting system for the supply chamber wherein the supply chamber is connected to the low pressure governor chamber when the control rod 51 is moved to its fuel shutoff position. I prefer to vent the uppermost part of the supply chamber, and the structure for accomplishing this includes a groove 61 in pump head 24 placing the annular cavity 62, defined by recess 66 and annular seal ring 63, in constant fluid communication with the supply chamber 19. A vent passage 64 is drilled between recess 66 and the bore 67 in housing 13 in which control rod 51 is mounted. A flat 68 milled on control rod 51 provides a port and converts a portion 69 of the control rod 51 into a control valve. When the control rod 51 is in its fuel delivery or idle position, as shown in FIGS. 1, 2 and 3, the cylindrical outer surface of rod 51 blocks vent passage 64 thus preventing flow of fluid from supply chamber 19 to governor chamber 18 via the vent passage 64. Flow through the vent passage 64- is permitted in the shutoff position (FIGS. 4 and 5) of rod 51 since the recess formed by flat 68 places vent passage 1 A conventional breather 80 permits escape of the air from reservoir 36.

The control rod 51 is manually operable by the operator at the control station 71, illustrated in FIG. 5, through a manually controlled push-pull rod 72 shiftable between pump idle (fuel delivery) and pump shutoff positions. In the pump idle position of the control rod 51, as illustrated in FIGS. 1, 2 and 3, the governor mechanism, not shown, is permitted to position the control rod 51 in response to changes in engine speed in a conventional manner. A throttle control 73 is provided to change the governed engine speed by acting on the governor control linkage in a conventional manner. The throttle control 73 and manual control for control rod 51 are shown schematically in FIG. 5.

From the foregoing description it is believed apparent that I have provided an extremely useful venting arrangement for the supply chamber 19 of a fuel injection pump 11 which permits the operator to selectively vent the supply chamber by moving the control rod 51 to a fuel shutoff position. My invention provides means whereby the supply chamber is automatically vented when the operator shuts down the engine in the normal way, that is, by movement of the control rod 51 to its shutoff position. The illustrated venting arrangement does not reduce the supply chamber pressure during low speed operation, as is inherent in anopen vent arrangement. Further, it will be noted that my invention is particularly suited for venting the intermediate pressure zone (chamber 19) of the three pressure zones (chambers 41, 19 and 18) of a fuel injection pump to the low pressure zone 18.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fuel injection pump for delivering fuel to an injector by way of a delivery passage comprising a housing having wall means defining a supply chamber for maintaining fuel at above atmospheric and substantially below injection pressures, and V a manually operable pump control rod for controlling fuel delivery of said injection pump shiftably disposed in said wall means and movable between a fuel shutoff position in which said supply chamber is vented to the exterior of said wall means independently of said delivery passage and a fuel delivery position in which said supply chamber is not vented to the exterior of said wall means.

2.. In a fuel pump of the type having a pump plunger reciprocable in a bore to pressurize fuel to an injection pressure, a supply chamber for receiving fuel from a supply pump and means maintaining fuel in the supply chamber at an intermediate pressure, means for venting said supply chamber including a passageway independent of said bore having one end in fluid communication with said supply chamber and adapted at its opposite end for fluid communication with a low pressure chamber, and

a control valve disposed in controlling relation to said passageway and adapted for connection to a manually operated control element, said valve being shiftable by said control element from a first position in which fluid flow in said passageway is prevented to a second position in which fluid flow is permitted through said passageway from said supply chamber to said low pressure chamber.

3. In a fuel pump of the type having a pump plunger reciprocable in a bore to pressurize fuel to an injection pressure, a supply chamber for receiving fuel from a supply pump and means maintaining fuel in the supply chamber at an intermediate pressure, the combination,

, comprising:

a passageway independent of said bore having one end in fluid communication with said supply chamber and adapted at its opposite end for fluid communication with a low pressure chamber, and I a manually operable pump control member for controlling pump delivery shiftably mounted on said pump for movement between fuel delivery and fuel shutoff positions and having a valve portion in fluid flow controlling relation to said passageway, said valve portion preventing fluid flow through said passageway when said control member is in said fuel delivery position and permitting fluid flow through said passageway from said supply chamber to said low pressure chamber when said control member is in said fuel shutoff position.

4. In a fuel pump having a first zone for maintaining fuel at an intermediate pressure preparatory to delivery to a second zone where the fuel is pressurized to an injection pressure for delivery via delivery passages to injectors and a third zone adapted forconnection to a low pressure fuel reservoir, means for venting said first zone,

comprising: i

a fluid passage between said first and third zones,

a valve for controlling flow of fluid through said passage including a shiftable valve member having a closed position in which fluid is prevented from flowing through said passage and an open position in which fluid is permitted to flow through said passage, and

manually operable means for selectively shifting said valve member between said positions.

5. The structure set forth in claim 4 wherein said valve member is a fuel control rod operable to control pump delivery.

6. The structure set forth in claim 5 wherein said open position is a fuel shutoff position of the control rod wherein fuel is not pressurized to said injection pressure in said second zone.

7. The structure set forth in claim 5 wherein said control rod is shiftable axially between said open and closed positions.

8. The structure set forth in claim 7 wherein said open position is a fuel shutoff position wherein fuel is not pressurized to said injection pressure in said second zone.

9. A fuel pump comprising:

a housing having a supply chamber,

a bore opening at one end into said supply chamber and having a high pressure pumping chamber at its other end, and

a low pressure chamber,

a plunger reciprocally mounted in said bore,

a vent passage in said housing connected at one end to the top of said supply chamber and at its other end to said low pressure chamber, and

control means for adjusting the pump delivery including a control member shiftably mounted in said housing for movement between first and second positions and having a valve portion disposed in fluid flow controlling relation to said vent passage, said valve portion preventing fluid flow through said vent passage when said member is in said first position and permitting fluid flow through said vent passage when said member is in said second position.

10. A fuel pump comprising:

a housing having a supply chamber,

a bore opening at one end into said supply chamber and having a high pressure pumping chamber at its other end,

a delivery passage connected at least intermittently to said pumping chamber, and

a low pressure chamber,

a pump plunger reciprocably mounted in said bore,

a vent passage in said housing connected at one end to the top of said supply chamber and at its other end to said low pressure chamber, and

a reciprocable control rod in said housing for adjusting the pump delivery including a valve portion in fluid controlling relation to said vent passage, said rod being shiftable to a pump delivery position in which fluid flow through said vent passage is.prevented and to a fuel shut-01f position in which fluid flow through said vent passage is permitted.

11. A fuel pump comprising:

a housing having a supply chamber for maintaining fuel at an intermediate pressure,

a bore opening at one end into said supply chamber and having a high pressure pumping chamber at its other end,

a plurality of delivery passages connected to said bore at circumferentially spaced intervals, and

a low pressure chamber,

a pump plunger reciprocably and rotatably mounted in said bore, said plunger having an inlet portion in said supply chamber and a distributor portion in said bore in fuel delivery flow controlling relation to said delivery passages,

a control sleeve surrounding the fuel inlet portion of said plunger, and

control means for adjusting said sleeve relative to said housing including a control member shiftably mounted in said housing for movement between fuel delivery and fuel shutofi positions and having a valve portion preventing fluid flow from said supply chamber to said low pressure chamber when said member is in said fuel delivery position and permitting fluid flow from said supply chamber to said low pressure chamber when said member is in said fuel shutoff position.

12. A fuel pump comprising:

a housing having a governor chamber at low pressure,

a supply chamber for maintaining fuel at an intermediate pressure,

a bore opening at one end into said supply chamber and having a high pressure pumping chamber at its other end, and

a plurality of delivery passages connected to said bore at circumferentially spaced intervals,

a pump plunger mounted in said bore having an inlet portion in said supply chamber and a distributor portion in said bore in fuel delivery flow controlling relation to said delivery passages,

means reciprocating and rotating said plunger in said bore,

a control sleeve surrounding the fuel inlet portion of said plunger,

a vent passage between the top of said supply chamber and said governor housing, and

control means for adjusting said sleeve relative to said housing ineluding'a control member shiftably mounted in said housing for movement between fuel delivery and fuel shutoff positions and having a valve portion in fluid controlling relation to said vent passage, said valve portion preventing fluid fiow from said supply chamber to said governor chamber through said vent passage when said member is in said fuel delivery position and said valve portion permitting fluid flow from said supply chamber to said governor chamber through said vent passage when said member is in said fuel shutoff position.

References Cited by the Examiner UNITED STATES PATENTS 2,123,950 7/1938 Lattner 103-42 2,980,092 4/1961 Dreisin etal 103-21 X FOREIGN PATENTS r 524,542 8 /1940 Great Britain.

ROBERT M. WALKER, Primary Examiner. 

1. A FUEL INJECTION PUMP FOR DELIVERING FUEL TO AN INJECTOR BY WAY OF A DELIVERY PASSAGE COMPRISING A HOUSING HAVING WALL MEANS DEFINING A SUPPLY CHAMBER FOR MAINTAINING FUEL AT ABOVE ATMOSPHERIC AND SUBSTANTIALLY BELOW INJECTION PRESSURES, AND A MANUALLY OPERABLE PUMP CONTROL ROD FOR CONTROLLING FUEL DELIVERY OF SAID INJECTION PUMP SHIFTABLY DISPOSED IN SAID WALL MEANS AND MOVABLE BETWEEN A FUEL SHUTOFF POSITION IN WHICH SAID SUPPLY CHAMBER IS VENTED TO THE EXTERIOR OF SAID WALL MEANS INDEPENDENTLY OF SAID DELIVERY PASSAGE AND A FUEL DELIVERY POSITION IN WHICH SAID SUPPLY CHAMBER IS NOT VENTED TO THE EXTERIOR OF SAID WALL MEANS. 